1. Field of the Invention
The present invention relates to a method for manufacturing a lightly-doped drain (LDD) type MOS (broadly, MIS) device and more particularly, to a method for manufacturing an LDD type CMOS device.
2. Description of the Related Art
In a fine-structured MOS device, in order to avoid deterioration of characteristics due to hot carriers, an LDD structure has been broadly used.
In a prior art method for manufacturing an LDD type CMOS device, after gate electrodes are formed on a PMOS area and an NMOS area of a semiconductor substrate, a shallow P type region is formed in the PMOS area by using a photoresist mask covering the NMOS area, and a shallow N type region is formed in the NMOS area using a photoresist mask covering the PMOS area. Also, after sidewall insulating layers are formed on sidewalls of the gate electrodes, a deep P type region is formed in the PMOS area by using a photoresist mask covering the NMOS area, and a deep N type region is formed in the NMOS area using a photoresist mask covering the PMOS area. This will be explained later in detail.
In the above-described prior art manufacturing method, however, four photolithography processes are required for an LDD structure, which increases the manufacturing cost.